This invention relates to an apparatus for producing ester.
An ester such as dibutylphthalate (DBP) or dioctylphthalate (DOP), which can be used as a plasticizer for polymers, is produced by a method including in order esterification, neutralization, distillation, decolorization and filtration. First, phthalic anhydride and alcohol such as butanol or octanol are heated so as to react whereby the monophthalate is produced. Next, to this reacted mixture is added sulfuric acid and benzene and then reacted at a boiling point so as to produce the diphthalate. This reacted mixture is neutralized by alkali and then distilled.
Since a Ti catalyst is used in producing the monophthlate, a by-product of Ti with an alkoxyl group is produced. Such a byproduct and Ti catalyst slightly remain in the distilled ester so that the ester is colored, thereby decreasing the quality. For such a reason, the distilled ester is decolorized with activated carbon for adsorbing the impurities. After that, the ester containing the activated carbon is filtered by a filter cloth coated with diatomaceous earth whereby the activated carbon can be removed from the ester so as to produce a final product.
The workability of the conventional ester production apparatus is not good because both the activated carbon and the filter msut be replaced and scrapped after. It also causes the production cost to increase.
If a nonuniform coating is formed on a filter cloth, the filtration accuracy is impaired so that final products can not have a high purity.